WEST INDIAN ISLANDS PORITES. 63 



Some 20 specimens were collected associated with Ocidina diffusa 1 var. Axhelia 

 mirahilis, and Mceandrina mceandrites ? young. 



A small specimen has been kindly presented to tins Museum by Dr. Vaughan. 



a. In four small fragments. Zool. Dept. 1906. 1. 1. 1. 



48. Porites Porto Rico 3. (J'. Porti- Rico wis tertia.) 



[Culebra, Ensenada Honda, coll. U.S. Fish Commission ; U.S. National Museum, Washington.] 



Syn. " Pmiks poriks forma clavaria Lamarck," Vaughan, Bull. U.S. Fish Commission for 1900, ii. 

 (1902) p. 316, pi. xxiv. and pi. xxxi. fig. 2. 



Description* — The corallum rises as a close cluster of stout, erect stems, without fusions. 

 They are faintly sinuous, and very gradually thicken as they rise, or perhaps we should say, 

 they are of very varying thicknesses, here slightly swollen, there constricted so that their 

 sides are irregularly wavy ; and they fork at small angles at about every 2 cm. apart ; the 

 prongs bending inwards so as to continue the erect growth. The stems are from 2 to 3 • 5 cm. 

 thick, the terminals about 2 cm. thick and about 2 cm. long. Only the tips are alive for about 

 3 cm. deep. Irregular bands of epitheca appear, often bending upwards as films over dying 

 edges. 



The calicles are about 2 mm. across, quite superficial, except that in the younger parts 

 the granules representing the septa and pali do not rise as high as those of the wall. The 

 wall is a very irregular zigzag, swelling at the angles into roughened granules, the uniting 

 thread being sometimes thick, sometimes thin, sometimes wanting. The septa show the same 

 characters : the formula is complete, but tha connections between the roughened granules — 

 septal and palic— are very iiTCgularly developed. Near the growing tips the granules are all 

 smooth and swollen portions of lamellate plates, the portions of which connecting the granules 

 seldom rising to the surface. The older the calicles are the larger are the granules and the 

 rougher, and the nearer to the surface rise the connecting pieces which grow thicker and 

 gradually rougher, like the granules. The varying sizes of the pali, owing to the irregularity 

 of their roughness somewhat obscures the symmetry of the formula. The usual five principals 

 can be made out, with an occasional, small, dorsal dii'ective and irregular disintegration of the 

 triplet. 



Where the surface has been abraded near the top, the smooth, continuous, lamellate 

 elements of the skeleton come to light, showing a well-developed spongy columella. The 

 central tubercle undergoes the same variations in size and appearance as the rest of the 

 granules. 



For the account of the types of Lamarck's Porites clavaria, as also of his Porites fur cata, 



* The details here given are taken from the excellent photographs given by Dr. Vaughan 

 above cited. 



